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Cluster Upgrade

 Upgrade Control Plane

Steps:

  • Update kubeadm package using package manager.
  • Drain the master node
  • Run kubeadm upgrade plan which runs some checks
  • Run kubeadm upgrade apply
  • uncordon the master node
  • update kubelet and kubectl 

Example with commands:

  • sudo apt-mark unhold kubeadm
  • sudo apt-get update
  • sudo apt-cache policy kubeadm
  • sudo apt-get install kubeadm=$TARGET_VERSION
  • sudo apt-mark hold kubeadm
  • kubectl drain c1-master1 --ignore-daemonsets
  • sudo kubeadm upgrade plan
  • sudo kubeadm upgrade apply v$TARGET_VERSION
  • kubectl uncordon c1-master1
  • sudo apt-mark unhold kubectl kubelet
  • sudo apt-get update
  • sudo apt-get install -y kubelet=$TARGET_VERSION kubectl=$TARGET_VERSION
  • sudo apt-mark hold kubectl kubelet

DEMO:

SSH to Master node
  • Run apt-get update 
  • Run apt-cache kubeadm        ==> available kubeadm versions
  • Run kubectl version --short   ==> what version we are on
  • Run kubectl get nodes           ==> lists all the nodes with kubectl version
  • Run sudo apt-mark unhold kubeadm
  • Run sudo apt-get update
  • Run sudo apt-get install -y kubeadm=$VERSION
  • Run sudo apt-unmark unhold kubeadm
  • Run kubeadm version
  • Run kubectl drain <hostname> --ignore-daemonsets  ==> ignore user workload on this master node. Above command evicts all the pods gracefully and spin up on other master node.
  • Run kubeadm upgrade plan  ==> show current version and planned upgrade version on two columns.
  • Run kubeadm upgrade apply  $VERSION
  • After the cluster upgrade, uncordon the node
  • Run kubectl uncordon $host-name

Worker Node Upgrade:

Steps:

  • Update kubeadm
  • Drain the node
  • Kubeadm upgrade node
  • Update kubelet and kubeadm
  • Uncordon Node.

Process:

  • kubectl drain c1-node1 --ignore-dameonsets
  • sudo apt-mark unhold kubeadm
  • sudo apt-get update
  • sudo apt-get install kubeadm=$TARGET_VERSION
  • sudo apt-mark hold kubeadm
  • sudo kubeadm upgrade node
  • sudo apt-mark unhold kubelet kubectl
  • sudo apt-get update
  • sudo apt-get install -y kubelet=$TARGET_VERSION kuebctl=$TARGET_VERSION
  • sudo apt-mark hold kubelet kubeadm
  • kubectl uncordon c1-node1

DEMO:

SSH to worker node:
  • kubectl drain <host-name> --ignore-daemonsets
  • sudo apt-mark unhold kubeadm
  • sudo apt-get update
  • sudo apt-get install -y kubeadm=$VERSION
  • sudo apt-mark hold kubeadm
  • sudo kubeadm upgrade node
  • once kubeadm is completed on worker node, upgrade kubelet and kubectl
  • sudo apt-mark unhold kubelet kuebctl
  • sudo apt-get update
  • sudo apt-get install -y kubectl=<VERSION same as kubeadm> kubectl=$VERSION
  • sudo apt-mark hold kubelet kubectl

Happy LearningšŸ˜€


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